1. Field of the Invention
This invention relates generally to active agent-containing polymeric materials which slowly release active agents, such as air fresheners, odorants, insecticides, insect repellants and the like, into the surrounding atmosphere, especially into room air, and to the process of preparing these materials.
More particularly, the invention relates to room air freshener products designed to gradually release the active agent into the air over sustained periods. The invention provides improved polymeric materials which gradually dispense the active agent, and which are clear and transparent, and if desired, can be made flexible and tacky at the surface. These properties permit the polymeric materials of this invention to be rolled and marketed in an assortment of convenient forms, such as in sheets or a strip dispenser from which the user can cut or tear off a portion which can then be readily and inconspicuously adhered to any convenient surface in a room. The active air freshener or odorant agent is then gradually released into the room over a sustained period, after which the material can be easily removed and replaced by fresh piece.
In the alternative, the polymeric materials of this invention can be made more rigid and, though clear, can be tinted and formed into, or made a part of, various decorative objects, such as pomanders, mobiles and artificial flowers and the like. For example, the polymeric materials of this invention can be used for the buds or petals of a flower, so that only these parts need be replaced when the active agent is exhausted.
2. Description of the Prior Art
It is well known that air fresheners, odorants, insecticides, insect repellants, and similar agents may be added to a room atmosphere for comfort, health, or other reasons, and the established marketability of such products has led to an ongoing search for improved vehicles for dispensing the active agents into the air.
Products which provide only for repeated instantaneous application, such as by aerosol dispensing means, are suitable for certain purposes, but are of limited usefulness where it is desired to provide continuous release of the active agent into a room atmosphere, and accordingly, there has been a recognized need to provide products which continuously and gradually release their active agents into the atmosphere while unattended.
Heretofore, air freshener products which automatically and gradually release the active agent into the air, have typically comprised bulky dispensers of various types containing only a small amount, e.g., a few percent, of active ingredient which, even if disguished as various objects or fixtures, are apt to be unnecessarily costly and often not as attractive as desired. The advantages of a clear, less bulky and completely inconspicuous material containing high levels of the active air freshener agent within the material itself e.g., from 5 to 20%, and in some cases as much as 50%, and which gradually and continuously releases the active air freshening ingredient into the surrounding atmosphere are thus apparent.
It is known that some types of polymeric materials can be used to entrap various ingredients within the polymer matrix, and that such ingredients can then be released gradually over sustained periods under certain conditions, such as in response to moisture in the case of hydrophilic polymers, and this has led to proposals to employ such polymers as vehicles for various active ingredients. For example, it has been proposed that polymers in the form of powders and films containing active agents which are nonsolvents in the polymer be incorporated into paints and wood treatments and the like, so that the nonsolvent agents form bubbles which gradually reach the surface to be released into the air (e.g., Seiner, U.S. Pat. No. 3,655,129). After the active agent has been exhausted in such films, however, the film itself, which is opaque, remains on the surface to which it has been applied, which limits the usefulness of such techniques to applications or locations, such as closets, where the treated surface can be repeatedly repainted or sprayed with the material, without concern for continuing accumulation of the film.
In applications where it is desired to release the active agent in response to moisture, it has been proposed to use hydrophilic polymers which, when ground into powders, can be mixed with various ingredients to be thereafter released and replaced by the water drawn into the hydrophilic polymer (e.g., Shepard and Gould, U.S. Pat. No. 3,520,949, Examples 15a and 15b). Such mixtures can also be incorporated into the form of sprays or films for application to clothing, bandages, and similar materials (e.g., Shepard and Gould, U.S. Pat. No. 3,657,118). Similarly, if the hydrophilic polymer itself is made water soluble, the untrapped agent can be released upon dissolution of the polymers in water, such as in soaps, detergents, or similar applications (e.g., Gould and Shepard, U.S. Pat. No. 3,681,248 and U.S. Pat. No. 3,772,215). But these techniques are not suitable where it is desired that the active ingredient be gradually and continuously released without depending upon moisture as a primary means to activate or control the rate of release.
Moreover, previous proposals for polymeric vehicles for active agents employed as powders and sprays cannot be conveniently and inconspicuously applied in any desired location and then readily removed after the active agent is exhausted, unless by washing in the case of water soluble materials. Furthermore, even if a suitable hidden surface can be found where continued build up of the material will remain unnoticed, the inconvenience of repeatedly applying such products as paints, coatings or sprays, in such hidden locations, as well as the even greater inconvenience of occasional washing to remove them, remains a disadvantage.